Still trying to learn, need someone to check this for me

[sbelew]

So, I'm still trying to learn about subs and enclosure design, mostly for the knowledge. Don't plan on getting into this business, but I have to admit, it is fun learning to design enclosures and play around with different subs. So I've been trying to learn Winisd, Torres and Sketchup. I was wondering if one of the professionals wouldn't mind taking a look at my work and giving an honest opinion. I modeled and designed a slot ported box for 2 Boston G1's I got. I'm not going to build this, it is just an exercise in learning. I'm pretty sure the port is not right but not sure whats wrong with it/ here is a google sketchup picture and the Torres settings.

[DbDesigns]

the port width where it enters the chambers should be half the width of the total port width at the front of the box.

[mylows10]

the port width where it enters the chambers should be half the width of the total port width at the front of the box.

also some kind of divider at the back of the port where the two come together.will keep turbulence down

[sbelew]

I fixed the drawing in the first post. I'm only concerned with making sure I got all the numbesr right for now, cubic feet, port tuning, port length, measurements. Once I learn that, i will then start trying 45's dividers, etc, But thank you both very much for you comments. my brain is fried and my eyes are crossed at this point.

[DbDesigns]

I fixed the drawing in the first post. I'm only concerned with making sure I got all the numbesr right for now, cubic feet, port tuning, port length, measurements. Once I learn that, i will then start trying 45's dividers, etc, But thank you both very much for you comments. my brain is fried and my eyes are crossed at this point.

truth. Ive been designing 3+ boxes a day for the past week... everything looks good you just need to add the divider and the back of the port.

[sbelew]

Ok, I added the divider and put a couple 45's in just for the halibut. May not be enough divider or big enough 45's, but its a learning process right? I need to go back and change the numbers for adding that stuff but you get the idea. Thanks Ranger, so I actually got it right, after only about 7 hours of learning and designing as I go? updated the pic in post 1 again.

[sbelew]

Here is the second one I done, same Boston G1 subs, but with round ports this time.
2.61 Cu ft Net
31 Hz tuned
2 ports, 4" x 22.5"
25" of port area. Just barely made the 9" to 13" per foot rule with 9.61" That can be tough to hit sometimes.

[sbelew]

I found the problem with the slot port on the enclosure in post #1 and corrected it.

Specs;
2.54 Cu Ft Net
29.5"w X 13"h X 19.5"d
31.49 Hz Tune
31.63 sq in of port area
barely made the port per foot rule at 12.46"
all brace and sub displacement accounted for

[DbDesigns]

stick with the slot... dont mess with aeros. also I prefer a little bit more port area per cu ft but as long as you are between 12-18 you should be fine. nice work.

[sbelew]

I've been playing around with getting the port area per sq ft up but haven't quite got it figured out. any suggestions on where I need to adjust to accomplish this?

[DbDesigns]

I've been playing around with getting the port area per sq ft up but haven't quite got it figured out. any suggestions on where I need to adjust to accomplish this?

make the port a little bit bigger, usually and inch or 2 wider wont take up too much space..

[sbelew]

It's amazing how much changing the port width effects the volume of the box. I have to adjust port length and the volume to retain my 2.6 cu ft. How important is it to retain the manufacturer suggested amount of volume if I can hit the desired port tuning and inches of port per sq ft ? And if I can go smaller, is there a general rule to follow?
I increased the port width and length, and increased the box depth till I found a little better sweet spot.

29.5"w X 13"h X 22"d
2.51 cu ft net
31.97 Hz with 17.19" of port per foot
port dimensions 3.75" wide X 38" length

[OmegaBunny]

Generally the manufacturers suggestions are smaller than what would would actually want, or I have found this to be true from practice and speaking with other designers/builders. I'm not sure about how it all works scientifically but I have had by boxes built to give me 1.5 cu ft for a 10, 2.5 for a 12, and I am currently using 4.5 for my 15". The new box for my 18" SA Z will be 5.5'. Sundown recommends 4 ft for the Z but ProRabbit recommended 5.5. Of course the size of the box also depends on the intended use and how much power it is going to be seeing also.

If I am wrong please correct me, I don't like giving out bad info.

[sbelew]

That makes sense. Manufacturers probably tend to err on the side of caution. It does seem that at least some of the builders around these parts tend to go between 10 and 20% larger than suggested. I stayed as close to suggested as I could, mainly because if I were to use this box in my car, I don't know that any bigger would even fit and retain at least some usable trunk space.